MCP23017 I2C C Code

[fehrenbach]

I am attempting to interface a MCP23017 to the Raspberry Pi using C code. I can communicate with the device using Linux i2c-tools commands icset and icget.

The problem is that I'm having difficulty finding C code that I can understand that will do the same thing. The code needs to let me specify the register that I read or write to using a variable. I have seen simple code that interfaces with a PCF8574 but it doesn't seem to let me specify the register that I am communicating to within the device.

Paul

[DougieLawson]

http://wiringpi.com

[BAStumm]

More specifically, http://wiringpi.com/extensions/i2c-mcp23008-mcp23017/

[fehrenbach]

Thanks,

I'm having a problem with header locations. My program is in ...programming/i2c
I use the -lwiringPi option at the end of the compile line. I get a compile error cannot find -lwiringPi.
I'm somewhat new to C and have also tried to locate copies of the wiringPi.h and mcp23017.h files in /usr/local/include
That doesn't work either.

[DougieLawson]

Have you installed wiringPi? It's not a built-in component.

http://wiringpi.com/download-and-install/